Efficient and selective removal of uranium(VI) from aqueous solution by ethylenediamine- and amidoxime-decorated Aspergillus niger

The ethylenediamine-modified Aspergillus niger (EMAN) and amidoxime-modified A. niger (AMAN) had been successfully prepared and then characterized by means of FTIR and SEM–EDX. The selective adsorption features of raw A. niger (RAN), EMAN, and AMAN for UO22+ over other coexistent heavy metal ions, such as Fe3+, Pb2+, Cu2+, Zn2+, Cd2+, and Co2+ had been investigated in a multi-metal system and a binary system. At the optimum pH which was 5, the orders of selectivity biosorption of EMAN and AMAN in a multi-metal system were UO22+ ≫ Fe3+ > Pb2+ > Cu2+ > Zn2+ > Cd2+ > Co2+ and UO22+≫ Fe3+ > Cu2+ > Pb2+ > Zn2+ > Co2+ > Cd2+, respectively. In a binary system, Fe3+, Pb2+, and Cu2+ suppressed the biosorption capacity of EMAN and AMAN for U(VI), while there was very slight interference from Zn2+, Co2+, and Cd2+ with the biosorption for U(VI). From the selectivity coefficients in both multi-metal and binary system, EMAN and AMAN prefer to uranyl ion than other metal ions, which were much better than RAN. As expected, the results indicated that the modified A. niger could be the effective and selective biosorbent for uranyl ion.